Cell Division

• Where are chromosomes found in eukaryotic cells?

  nucleus
• Where are chromosomes found in prokaryotic cells?


  cytoplasm
• chromosome


  coiled thread-like structure of DNA
• Genes

  Sections of DNA that contain the code for a particular protein.
• Where are genes found?

  Chromosomes
• what arrangement are chromosomes found normally in body cells?

  Pairs
• Cell Cycle


  The series of stages where a cell divides
• The 3 stages of mitosis in order


  Interphase - Cell growth

  Mitosis - Nucleus divides

  Cytokinesis - Cell membrane & cytoplasm divide making two identical daughter cells
• How many chromosomes (after DNA replication) will be present in a cell?

  46 Pairs
• What needs to happen within the cell before it can divide?

  DNA replication

  Cell organelles replication
• Stem cell


  An undifferentiated cell capable of giving rise to many more cells of the same type.
• Function of stem cells in embryos


  To develop into multiple cell types aiding in the development of the embryo into a mature organism.
• Function of stem cells in adult animals

  To be the source of cells used in growth and repair of the mature animal.
• Function of stem cells in plant meristems.


  To allow a plant to keep growing throughout its life by specialising into any type of cell
• Why are embryonic stem cells useful?

  They can be cloned and made to differentiate into most different types of human cells.
• Location of adult stem cells

  Bone marrow
• Difference between adult stem cells and embryonic stem cells

  Embryonic stem cells can differentiate into all cell types
• When does meristem tissue in plants differentiate?


  The whole life of the plant
• Potential use of stem cells in medicine

  To treat conditions where cells have been damaged e.g. diabetes, paralysis
• Principle of therapeutic cloning


  An embryo is produced with the same genes as the patient.
• Advantage of therapeutic cloning

  No rejection of the new cells by the patient (as they are the patient’s own cells).
• 2 Potential problems with therapeutic cloning.

  Risk of viral infection

  Ethical objections to killing of embryos
• How are plant stem cells used in horticulture (commercial plant growing)?

  To create plant cuttings
• 2 Advantages of the use of clones in horticulture.

  Rare species cloned to prevent exctinction

  Crops with special adaptations can be identically produced in large quantities